#!/usr/bin/node
const argv=process.argv[2],
      log=console.log;

//validata argv

//1 argv number equal 3
if(argv===undefined){
  log('cmd exit-code');
  process.exit(2);
}
//code is number
if(isNaN(Number(argv))){
  log('argv must be number');
  process.exit(3);
}
    
//code range>0
if(Number(argv<=0)){
  log('argv must > 0');
  process.exit(4);
}
process.exit(argv);

//没有做错误处理
